The prior art for this invention may be grouped as follows:    I. U.S. Pat. Nos. 5,471,721, 5,632,841, 5,849,125, 6,162,313, 6,042,345, 6,060,811, and 6,071,087 showing either prestressing of piezoelectric actuators, or dome-shaped piezoelectric actuators, or both. This prior art is generally in apposite because the present invention does not use a prestressed or dome-shaped piezoelectric actuator.    II. U.S. Pat. Nos. 6,179,584, 6,213,735, 5,271,724, 5,759,015, 5,876,187, 6,227,809 showing so-called micropumps. Such pumps generally pump only a drop of fluid at a time; because of the small forces and low Reynolds numbers involved, this prior art is generally in apposite.    III. U.S. Pat. Nos. 4,034,780, 4,095,615 showing flapper valves. These are flappers mounted on a separate hinge. No prior art was found showing a flex valve with a miniature pump.    IV. U.S. Pat. Nos. 5,084,345, 4,859,530, 3,936,342, 5,049,421 showing use of polyimide adhesives for various purposes, including bonding metals and other materials to film.    V. U.S. Pat. Nos. 4,939,405, 5,945,768 showing electrical driver circuits for piezoelectric actuators.    VI. U.S. Pat. Nos. 6,227,824, 6,033,191, 6,109,889, German WO 87/07218 showing various kinds of pumps incorporating piezoelectric actuators.